yes, when the feed is over 6 m/min a suddent stop in step pulses trip a servo error
I tuned the servos when I build the machine and when I wrote the controller software, so Im sure they are tuned properly, I know the machine capabilities from the day I designed it, I just never was able to use it with the full potential before
the PID is tuned to keep minimum folowing error, so when mach3 stops suddently, they try to stop suddently as well, that shakes the whole machine too much, therefore mach3 shuould never stop suddently, it should ALWAYS use ramps
allowing more folowing error is not the solution, the machine run smooth as the step pulses are smooth, if the step pulses are NOT smooth, then the problem is where they are generated, you can try to calculate the overshoot whrere the speed is 6m/min and the deceleration of 0.2 sec is missing, It will be about 8mm if the servo controller decelerate, insted of mach3, this is completely unacceptable for CNC machine,
I think it will be easy for you to understand if the motors are STEPPERS then there is nothing to tune, they will just loose steps if you dont send proper step pulses
therefore I decided to locate and solve the problem instead of looking for a way to work with it, the main job of the motion software is to generate pulses WITH ramps
reading your message again make me think for the difference between good product and bad product (machine/software), good product is working as it should be, and bad product is when you try to make it work with all unsolved problems in it, if you want to make a good product, then you should solve the problems, instead of trying to go round